1. Field of the Invention
The present invention relates to a wafer inspection apparatus and, more particularly, to various types of structures for realizing a reduction in convey time of a wafer as an inspection target, an improvement in operability, or the like.
2. Related Background Art
A conventional wafer inspection apparatus has at least a microscopic observation system in order to observe a wafer serving as an inspection target by using a microscope. In order to realize automatic microscopic observation of the wafer, the conventional wafer inspection apparatus generally has a function of temporarily storing the wafer and a structure for conveying the wafer to a desired position to microscopically observe it.
An object of the present invention is to provide a wafer inspection apparatus having various types of structures for realizing a reduction in convey time of a wafer as an inspection target, an improvement in operability, or the like. A wafer inspection apparatus according to the present invention has at least a wafer convey system and a microscopic observation system to realize efficient wafer observation.
More specifically, in the wafer inspection apparatus according to the present invention, as shown in FIGS. 1 to 3, at least a first convey system 4 and a second convey system 5 prepared as the wafer convey system, and a macro observation system 6 and a microscopic observation system 7 prepared as the observation system are mounted on a main flat surface 1a of an operation board 1 on which an input unit 100, e.g., a pointing device, is provided. This wafer inspection apparatus is also provided with a monitor 8 for displaying a desired image, e.g., control information, character information, or the like, regarding operation for wafer inspection.
Most of these systems mounted on the operation board 1 are covered with a cover 9 except at least the observation systems 6 and 7, to ensure the safety of the person, the operator, or the like who is in charge of wafer inspection. The portions that handle the wafer are exposed from a major surface 90 of the cover 9 through a plurality of openings 92 and 94 (see FIG. 2). Accordingly, the wafer serving as the inspection target is conveyed through the space above the main surface 1a of the operation board 1. Thus, in this specification, the main surface 1a of the operation board 1 corresponds to a wafer convey reference surface of the wafer inspection apparatus according to the present invention. Each lifting unit 2 has a driving system for moving its setting surface 2a in a direction perpendicular to the main surface 1a as the wafer convey reference surface.
The wafer inspection apparatus according to the present invention has the lifting units 2 on a power supply unit 11. Each lifting unit 2 has the setting surface 2a on which a cassette member 3 for storing wafers can be set, and positions the cassette member 3 at a predetermined position while holding it.
In particular, when the cassette member 3 is set a on the setting surface 2a of the lifting unit 2, the setting surface 2a is positioned, with reference to the main surface 1a of the operation board 1 of the wafer inspection apparatus, at a position lower than the observation reference surface on which the conveyed wafer is set. In this manner, since the cassette member 3 storing the wafers can be set on the lifting unit 2 easily, a physical burden to the operator or the like who handles the cassette member 3 can be reduced, thereby improving the operability of the wafer inspection apparatus. In other words, as shown in FIG. 1, the position Q2 corresponding to a mount surface of the operation board 1 on which the cassette member 3 is set is lower than the position Q1 corresponding to the main surface 1a of the operation board 1. Therefore, the mount surface (position Q2) on which the lifting unit 2 is set is positioned at a lower position than the main surface 1a (position Q1) in the direction perpendicular to the main surface 1a. The lifting unit 2 can position the setting surface 2a at a lower position than the main surface 1a of the operation board 1. In this specification, the observation reference surface means a plane including a main surface 60a (see FIG. 17) of a wafer stage 60, that holds the wafer, of the macro observation system 6 for allowing visual inspection by the observer, or a main surface 741 (see FIG. 18) of a holder 740, that holds the wafer, and in parallel with respect to the main surface 1a of the operation board 1.
A plurality of types of cassette members 3 having different sizes (e.g., a 4-inch wafer cassette member and a 8-inch wafer cassette member) can be set on the setting surface 2a of the lifting unit 2, respectively. The lifting unit 2 has a first detector 20a and a second detector 20b. The first detector 20a is provided in an area of the setting surface 2a where a first area AR1 which is in contact with a small cassette member and a second area AR2 which is in contact with a large cassette member overlap. The second detector 20b is provided in a portion of the second area AR2 which does not overlap the first area AR1. The first detector 20a outputs a first detection signal when a cassette member of any size is set on the setting surface 2a of the lifting unit 2. The second detector 20b outputs a second detection signal when a large cassette member is set on the setting surface 2a of the lifting unit 2.
With this arrangement, a main controller 10 can determine that a small cassette member is set on the lifting unit 2 when it receives the first detection signal from the first detector 20a and does not receive the second detection signal from the second detector 20b, and can determine that a large cassette member is set on the lifting unit 2 when it receives the first and second detection signals from both of the first and second detectors 20a and 20b. The main controller 10 controls the input unit 100, e.g., a pointing device 1b or a keyboard 1c, the lifting unit 2 including the first and second detectors 20a and 20b and the driving system for moving the setting surface 2a, the microscopic observation system 7 including the X-Y stage 71 (see FIG. 18), the macro observation system 6 including a driving system (see FIG. 17), the first convey system 4 including a driving system (see FIGS., 10, 15 and 16), the second convey system 5 including the driving system (see FIG. 22), and the monitor 8 in a centralized manner, as shown in, e.g., FIG. 3.
As described above, this wafer convey system includes the cassette member 3 set on the lifting unit 2, the first convey system 4 for conveying wafers between the cassette member 3 and a predetermined area located between the cassette member 3 and the observation system, and the second convey system 5 for conveying wafers between the predetermined area and the observation system. Further, the first convey system 4 extracts and stores the wafers from and in the cassette member 3. In particular, each of the convey systems 4 and 5 has a mechanism for conveying the wafers while correcting a difference between the setting surface 2a and the observation reference surface 741 (or 60a) in a direction perpendicular (in the direction of height) to the main surface 1a (the wafer convey reference surface) of the operation board 1.
The first convey system 4 has, as shown in FIG. 10, a first arm portion 48, a second arm portion 49, and a support portion 41. The first arm portion 48 extracts a wafer as an inspection target from the cassette member 3 set on the lifting unit 2 and holds the extracted wafer. The second arm portion 49 holds the wafer inspected by the observation system 6 and 7, and stores the inspected wafer in the cassette member 3. The support portion 41 holds the first and second arm portions 48 and 49 to be spaced apart from each other by a predetermined distance in a direction perpendicular to the wafer convey reference surface. In particular, the support portion 41 includes a height correction mechanism for moving the first and second arm portions 48 and 49 independently of each other in the direction perpendicular to the wafer convey reference surface while it holds them. In this manner, in the wafer inspection apparatus according to the present invention; since the first convey system 4 has the first and second arm portions 48 and 49 operable independently of each other, efficient wafer conveyance is realized.
This height correction mechanism includes a driving source 42 and a cam mechanism 410, as shown in, e.g., FIGS. 11 to 13. The driving source 42 drives the cam mechanism 410 in order to supply a driving force in the direction perpendicular to the wafer convey reference surface to the first and second arm portions 48 and 49. The cam mechanism 410 moves the first and second arm portions 48 and 49 independently of each other in the direction perpendicular to the wafer convey reference surface. Furthermore, the cam mechanism 410 is provided with a first cam groove 410a and a second cam groove 410b (see FIG. 14). The first cam groove 410a serves to move the first arm portion 48 in one direction perpendicular to the wafer convey reference surface. The second cam groove 410b can move the second arm portion 49 in a direction perpendicular to the wafer convey reference surface and opposite to the moving direction of the first arm portion 48. Movement control of each of the first and second arm portions 48 and 49 in the direction perpendicular to the wafer convey reference surface is performed by the main controller 10 in accordance with the size of the wafer as the inspection target.
More specifically, the first arm portion 48 has a first arm head 48a for holding the wafer, a first support arm 43 which is supported by the support portion 41 and supports the first arm head 48a, and a driving mechanism provided in the first support arm 43. The driving mechanism in the first support arm 43 moves the first arm head 48a in parallel with respect to the wafer convey reference surface and the first support arm 43 relative to the support portion 41 and in parallel with respect to the wafer convey reference surface. Similarly, the second arm portion 49 has a second arm head 49a, a second support arm 44, and a driving mechanism for moving the second arm head 49a. 
Furthermore, as shown in, e.g., FIGS. 22 to 26, the second convey system 5 has a plurality of rotary arm portions 51a to 51c, a support shaft 50, and a driving mechanism. The plurality of rotary arm portions 51a to 51c can hold the wafer. The support shaft 50 supports the plurality of rotary arm portions 51a to 51c at its distal end portion and extends in the direction perpendicular to the wafer convey reference surface. The driving mechanism integrally rotates the plurality of rotary arm portions 51a to 51c by rotating the support shaft 50.
More specifically, the driving system of the second convey system 5 has first and second cam mechanisms. The first cam mechanism rotates the support shaft 50 at a predetermined timing (see FIG. 24). As shown in FIG. 26, the second cam mechanism pushes up at least a selected one of the plurality of rotary arm portions 51a to 51c in the direction perpendicular to the wafer convey reference surface (corresponding to the main surface 1a of the operation board 1). The rotary arm portion 51a has a rotary arm head 510a capable of holding the wafer, and an engaging member (including at least a support member 511a and a guide receptacle 512a) for supporting the rotary arm head 510a. This engaging member is slidably attached to a linear guide 50b provided on the side surface of the support shaft 50 in the direction perpendicular to the wafer convey reference surface. Other rotary arm portions 51b and 51c have the same structure.
Since the first and second convey systems 4 and 5 have the above arrangement, the first position where the wafer is transferred from the first convey system 4 to the second convey system 5 and the second position where the wafer is transferred from the second convey system 5 to the first convey system 4 are shifted from each other in the direction perpendicular to the wafer convey reference surface (FIGS. 33 and 34).
The present invention will be more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only and are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will be apparent to those skilled in the art from this detailed description.